1. Field of the Invention
The present invention relates generally to a camera back for large format cameras, otherwise known as view cameras, and more particularly to a locking mechanism for changing various attachments used with the camera back.
2. Description of the Prior Art
The large format camera, or view camera, has been in use for many years. Its relatively unchanged design from the turn of the century is still widely used by professional and amateur photographers even with the advent of the digital camera and convenient automatic cameras. The advantage of using a large format camera is that the film surface is much larger than that of an automatic camera, and its clarity is much sharper than a digital camera. Accordingly, higher quality pictures that can be enlarged with greater ease are achievable with large format cameras.
Digital backs have now been introduced to be attached to the large format camera to take advantage of the clarity characteristics that are inherent with a large format camera. These digital backs allow the large format camera to take digital pictures while still maintaining the advantage of having a large film surface to take clear pictures.
The large format cameras typically have a camera back attachment that is secured to the camera body itself. The camera back is used as the actual interface between the camera body and the ground glass and later the film.
However, in order to understand the use of the camera back, the process of taking an actual picture must be explained. First, the camera body itself must be set up to face the subject to be photographed. Second, the camera must be focused. In order to focus the camera, the ground glass attachment must be used. The ground glass attachment is merely a piece of glass with a rough surface on the inside and an imprint of either a grid or a cross-hairs image to aid in positioning the camera. The ground glass is typically attached to the camera back using a commonly known sliding lock back.
The sliding lock back is the standard back that is used on almost all of the large format cameras in use today. The sliding lock back has two sliding locks, one on the top and one on the bottom that are engaged by sliding the locks in one direction to engage the attachment. Specifically, the locking mechanism is two sliding flat pieces of metal attached to the camera back. The flat pieces of metal have protrusions on the edge to grip the item placed in the camera back when engaged. The pieces of metal are attached to the camera back with two screws each. The pieces of metal are guided by the screws to only move in a diagonal direction to either engage or disengage an item in the camera back. In this instance the ground glass is held in place by sliding the locks into the engaged position.
Once the ground glass is locked in place, the camera shutter is opened so that the image of the subject is projected onto the ground glass. The photographer then focuses the camera so that the image on the ground glass is precisely what will be photographed. It is important that the camera is properly focussed, as the quality of the image on the ground glass is exactly what will be photographed on the film. The shutter is then closed and the ground glass is unlocked from the sliding lock back by disengaging the two locks and then the film is loaded.
The film for the large format camera can be stored in a variety of formats, such as a magazine that holds two or more sheets of film flat, a rolled film type cartridge, an instant development type film holder or a digital back. Each type of film is unique in its own way, however, each film must be attached to the camera back in the same manner. Specifically, the film is attached to the camera back in the same manner as the ground glass, so the process of loading the film is exactly the same as loading the ground glass.
It is extremely important that the camera stay absolutely still while removing the ground glass and inserting the film. Since, any movement of the camera may cause the camera to no longer be in focus on the proper subject. After the film is properly inserted in the camera and then locked into place using the sliding lock back the picture may then be taken.
The inherent problem with the sliding lock back is that there are two opportunities for the camera to move, namely, when the ground glass is removed and when the film is loaded. During both instances, the sliding lock back has to be either engaged or disengaged using two separate sliding locks on the camera back. The locking process requires the photographer to remove both hands from stabilizing the camera to then disengage or engage the locks and to then remove or insert the ground glass or film.
When the photographer removes both hands from the camera, the chances of the camera being inadvertently shaken or moved is greatly increased. In addition, the act of having to unlock or lock a separate top and bottom lock with no hands on the camera body itself further increases the chances of the camera moving.
One camera back design has attempted to solve the problem of requiring the release of the locks before loading the film. In this design, the ground glass is attached to the sliding lock back, however, in order to load the film the locks do not have to be disengaged. Instead, the ground glass is attached to the camera back using a spring loaded hinge mechanism. This mechanism allows the ground glass to be held firmly in place while focussing. When the image is focussed, a cartridge type film or instant development type film can be inserted between the ground glass and the camera back. The ground glass hinge pivots so that the film cartridge is then held in place between the ground glass and the camera back. This design eliminates the problem of using two hands to load or remove the ground glass and film, however it creates a new problem. Since the ground glass is connected by a spring loaded hinge, one must push the film between the ground glass and the camera back to overcome the tension on the spring itself. The act of pushing the film in shakes the camera since considerable force must be applied to load the film. In addition, the spring loaded ground glass design does not allow the rolled type film or digital back to be loaded. Thus, the film must be loaded by first removing the spring loaded ground glass attachment.
In order to overcome the inherent problems with both designs, it would be desirable to have a locking camera back that could be operated with one hand on the camera at all times thus reducing the chances of the camera moving. Furthermore it would be desirable to have a locking mechanism that locks the film or ground glass to the camera back and does not require either excessive force or the separate acts of engaging and disengaging multiple locks.
It is an object of the present invention to provide a simple and convenient locking camera back for a large format camera.
It is a further object of the present invention to provide a locking camera back with multiple locks that are operated simultaneously by one mechanism.
It is still a further object of the present invention to provide a lock for a camera back that, when engaged and disengaged, firmly holds components of the camera, but does not require excessive force or manipulation.
In accordance with one form of the present invention, the camera back generally includes a frame for receiving a camera component and a locking arm pivotally connected to the frame with an engagement surface for holding a camera component securely to the frame. Preferably the locking arm is attached to the frame with mounting blocks with the locking arm biased into a locked position by a compression spring. The locking arm preferably comprises a top and a bottom locking member positioned parallel to the top and bottom frame members with the locking members connected by a handle. Compression springs are attached between the handle and the frame to push the handle in an upward position. A tension device is attached to the frame so that after the camera component is locked into place on the camera back, the tension device effectively maintains the locking arm in a locked position to avoid inadvertent unlocking. The locking arm in the preferred embodiment of the invention is pivotally mounted so that the locking arms are positioned inside the outer peripheral edge of the frame. Alternatively, the locking arms are pivotally mounted to the outside peripheral edge of the frame. In another alternate embodiment the locking arms have an engagement surface that is bent inward toward the center of the frame so that the camera component can be securely held in place.
A method for releasably attaching a camera component to the back of a camera preferably including the steps of pivoting a locking arm having an engagement surface out of engagement with a frame formed on the camera back and placing the camera component within the frame. The locking arm is then released so that the engagement surface holds the camera component securely in the frame.
A preferred form of a camera back for a camera and method of use, as well as other embodiments, objects, features and advantages of the invention will be apparent from the following detailed description of illustrative embodiments thereof which is to be read in conjunction with the accompanying drawings.